The glycemic index: what is it and how does it affect your health and weight? Here’s everything you need to know.



The glycemic index (GI) is a rating of how quickly carbohydrate-containing foods break down to simple sugars. High glycemic carbohydrates break down quickly into glucose, resulting in a rapid rise in our blood sugar level. On the other hand, slow releasing, low glycemic carbohydrates break down relatively slowly, providing a more sustained release of energy.


The GI rates all carbohydrate containing foods, including those like vegetables, pulses and high sugar treat foods, as well as carbohydrates we typically think of like pasta, bread, rice and potatoes.



If you want consistent energy levels, good concentration and to manage your weight, understanding the glycemic index is important. It’s also key for ensuring good metabolic health. Poorly regulated blood sugar has been linked to a number of chronic degenerative diseases, most notably diabetes.
A high GI diet leads to marked peaks and dips in blood sugar levels. When our blood sugar levels are elevated, insulin is release. This hormone transports sugar from the blood stream into cells to be used for energy. If we have an immediate need for that energy, say if we are exercising, the sugar would be used to fuel our workout. But if we don’t, the sugar will be stored for later use. It can be stored as glycogen in muscle and liver cells, but it can also be converted into triglycerides and stored in fat cells.


While the glycemic index gives an average rating of the impact of that food on our blood sugar, it’s important to remember that different people react differently to different food. Two people could have a very different response to the exact same food. Various factors in our makeup can influence how quickly we break down carbohydrate foods into simple sugars.
For example, I am aware that I am particularly sensitive to carbohydrates. Though DNA and gut bacteria testing, I know that my body will rapidly convert carbohydrates into simple sugars, putting me at greater risk of weight gain and diabetes if I eat a high glycemic diet, compared to those who are not so sensitive.
The portion size we consume is another important consideration, this is where ‘glycemic load’ (GL) comes in. The glycemic load takes into consideration a typical portion of a particular food whereas the glycemic index doesn’t.


What you eat with your carbohydrate can also affects it’s impact on your blood sugar level. Eating a carbohydrate food alongside sources of protein or fat can slow their release into the bloodstream




If you’ve ever experienced a mid afternoon energy slump, lack of concentration or cravings for sweet or starchy foods, chances are you know what a blood sugar dip feels like.


A low GI diet will provide you with slow releasing energy which will help keep you energised and mentally alert. It can also support weight loss by preventing excess sugar in the blood stream being converted into fat.



Go low. Stick to mostly low glycemic sources of carbohydrates day to day. Minimise your sugar intake and swap starchy carbohydrates for vegetables.


Moderate your portion size. Make carbohydrates a part of your meal, not the whole event.


Combine good quality sources of proteins and healthy fats with your carbohydrates to slow their release into the bloodstream.


Stay hydrated. Dehydration can lead to higher blood sugar levels. Yet another reason to drink up.


Monitor. If you’re serious about fuelling your body optimally, a blood glucose monitor is a great investment. I used Abbott’s Freestyle Libre to monitor my blood sugar levels for a period of time in order to understand exactly how my body responded to different foods.



Non-starchy vegetables and salad. Fill your plate with colourful, seasonal veg. Think roasted Mediterranean vegetables, stir fries, ratatouille and vegetable curries.
Pulses. Lentils, beans and chickpeas are incredibly versatile. They also provide protein as well as carbohydrates making them a great post run refuel option.
Grains and pseudograins. Barley, buckwheat, black and brown rice, whole rolled oats, rye, quinoa. These make a great addition to salads and soups.

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